A novel multiscale approach to predict the mechanical behavior of polycrystalline Ni-based superalloys
Multiscale modeling of polycrystalline metallic alloys has been carried out by homogenization of the single crystal behavior by means of mean-field approximations or, more recently, computational homogenization.The key ingredients to predict the polycrystal behavior are the microstructural features (grain size, shape and orientation distribution) and the mechanical properties of the single crystals.While the former can be accurately determined by means of advanced 3D characterization techniques (such as serial sectioning and X-ray microtomography together with electron back-scattered diffraction and X-ray diffraction), the main uncertainty comes from the actual properties of the single crystals within the polycrystal.In this investigation, the mechanical properties of a wrought polycrystalline Ni-based superalloy were predicted by means of a combination of micromechanical tests (to obtain the single crystal properties within the polycrystal) and computational homogenization.To this end, micropillars with diameters in the range 1 to 18 μm were milled from the polycrystal by means of FIB and tested in different orientations (suitable for single and multiple slip) as a function of strain rate and temperature.This information was used to calibrate the parameters of a phenomenological single-crystal plasticity model.In parallel, a three-dimensional representative volume of the polycrystalline microstructure was built using Voronoi tessellation.The initial distribution of points for the Voronoi tessellation is optimized by means of a Monte Carlo algorithm to fit the experimental grain size distribution of the polycrystal.The effective polycrystal behavior was computed by means of the numerical simulation of the mechanical response of the representative volume element of the microstructure with periodic boundary conditions and compared with experimental results of the polycrystalline material.The dominant mechanisms that control the mechanical behavior of Ni-based superalloys and the potential of this approach to predict the mechanical properties (strength, creep, fatigue) of Ni-based superalloys were discussed to the light of the comparison between simulations and experiments.
Multiscale modeling Ni-based superalloy Polycrystalline metallic alloy Mechanical behavior
Javier LLorca
IMDEA Materials Institute & Polytechnic University of Madrid,Spain
国际会议
2015 International Symposium on Structural Integrity(2015年国际结构完整性学术会议)
沈阳
英文
9-10
2015-05-16（万方平台首次上网日期，不代表论文的发表时间）